RosettaCodeData/Task/Date-format/68000-Assembly/date-format.68000

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JSR SYS_READ_CALENDAR ;outputs calendar date to BIOS RAM
MOVE.B #'2',D0 ;a character in single or double quotes refers to its ascii equivalent.
JSR PrintChar
MOVE.B #'0',D0
JSR PrintChar
LEA BIOS_YEAR,A1
MOVE.B (A1)+,D0 ;stores last 2 digits of year into D0, in binary coded decimal
JSR UnpackNibbles8 ;separate the digits into high and low nibbles: D0 = 00020001
ADD.L #$00300030,D0 ;convert both numerals to their ascii equivalents.
SWAP D0 ;print the "2" first
JSR PrintChar
SWAP D0 ;then the "1"
JSR PrintChar
MOVE.B #'-',D0
JSR PrintChar
MOVE.B (A1)+,D0 ;get the month
JSR UnpackNibbles8
ADD.L #$00300030,D0
SWAP D0
JSR PrintChar
SWAP D0
JSR PrintChar
MOVE.B #'-',D0
JSR PrintChar
MOVE.B (A1)+,D0 ;get the day
JSR UnpackNibbles8
ADD.L #$00300030,D0
SWAP D0
JSR PrintChar
SWAP D0
JSR PrintChar
;now the date is printed.
;Now do it again only written out:
jsr NewLine
CLR.L D0 ;reset D0
MOVE.B (A1),D0 ;A1 happens to point to the weekday
LSL.W #2,D0 ;we are indexing into a table of longs
LEA Days_Lookup,A2
LEA (A2,D0),A2
MOVEA.L (A2),A3 ;dereference the pointer into A3, which the PrintString routine takes as an argument.
JSR PrintString
CLR.L D0
LEA BIOS_MONTH,A1 ;GET THE MONTH
MOVE.B (A1)+,D0
LSL.W #2,D0
LEA Months_Lookup,A2
LEA (A2,D0),A2
MOVEA.L (A2),A3
JSR PrintString
MOVE.B (A1),D0 ;GET THE DAY
JSR UnpackNibbles8
ADD.L #$00300030,D0
SWAP D0
JSR PrintChar
SWAP D0
JSR PrintChar
MOVE.B #',',D0
JSR PrintChar
MOVE.B #' ',D0
JSR PrintChar
MOVE.B #'2',D0
JSR PrintChar
MOVE.B #'0',D0
JSR PrintChar
LEA BIOS_YEAR,A1
MOVE.B (A1)+,D0 ;stores last 2 digits of year into D0, in binary coded decimal
JSR UnpackNibbles8 ;separate the digits into high and low nibbles: D0 = 00020001
ADD.L #$00300030,D0 ;convert both numerals to their ascii equivalents.
SWAP D0 ;print the "2" first
JSR PrintChar
SWAP D0 ;then the "1"
JSR PrintChar
forever:
bra forever ;trap the program counter
UnpackNibbles8:
; INPUT: D0 = THE VALUE YOU WISH TO UNPACK.
; HIGH NIBBLE IN HIGH WORD OF D0, LOW NIBBLE IN LOW WORD. SWAP D0 TO GET THE OTHER HALF.
pushWord D1
CLR.W D1
MOVE.B D0,D1
CLR.L D0
MOVE.B D1,D0 ;now D0 = D1 = $000000II, where I = input
AND.B #$F0,D0 ;chop off bottom nibble
LSR.B #4,D0 ;downshift top nibble into bottom nibble of the word
SWAP D0 ;store in high word
AND.B #$0F,D1 ;chop off bottom nibble
MOVE.B D1,D0 ;store in low word
popWord D1
rts